This section provides background information related to the present disclosure which is not necessarily prior art.
The conventional multi-cooling heat exchanger includes a core portion having a plurality of tubes, a header tank attached to both ends of the tubes, a plurality of fins disposed between adjacent tubes and an insert or side plate that provides stability to the heat exchanger. The header tanks are separated along their length to provide two or more separate cooling sections for the heat exchanger. A first fluid flows through the first section of the header tanks and tubes and a second fluid flows through the second section of the header tanks and tubes. Typical examples of the first fluid is refrigerant from an air conditioning system and a typical example for the second fluid is transmission oil. Both fluids are cooled as they pass through the plurality of tubes.
These multi-cooler heat exchangers develop a high amount of thermal strain. This is due to one of the fluids having a higher operating temperature than the other fluid. This temperature difference leads to a higher thermal expansion in the cooling section which cools the higher temperature fluid. Since both sections of the tubes are constrained by the header tanks, thermal strain occurs.
To alleviate this thermal strain, it is known to saw cut one or both of the header tanks to allow the higher temperature fluid section to expand freely and reduce the thermal strain. This method is effective but it adds labor and production time to the process. Another method for reducing this thermal strain is to make a saw cut in the insert or side plate. During cold weather operation, the plurality of tube expand due to increased temperature and the insert or side plate tends to heat up at a slower rate which causes a second source of thermal strain. The saw cut in the insert or side plate reduces this thermal strain but it still requires additional labor and production time.